The real passion, and real story, of Jane Austen is found in personal letters

Thanks to Cassandra and her pyrotechnical ways, we know a lot less about her famous sister Jane than we otherwise would. In 1843 Cassandra, chief recipient of the novelist's letters, burned "the greater part" of them. Aunt Jane had too "open and confidential" a way of expressing herself, niece Caroline explained.

Fortunately, the overly protective Austen family deemed 160 of Jane's letters sufficiently anodyne, and spared them the flame. These tell us much of what we know of Austen's life.

In the first few surviving letters, written when Jane was 20, we get fragments of a budding romance with a handsome Irishman, Tom Lefroy. The flirtation ended badly. Twenty-year-old Tom, who was visiting relatives in Hampshire before heading off to London to study law, came from a family with little money. The Lefroys decided Jane, herself the daughter of an unmoneyed clergyman, wasn't rich enough, so they put the kibosh on the romance. Tom and Jane never saw each other again.

But this episode — the basis for Becoming Jane, the new movie starring Anne Hathaway and James McAvoy — fires the imagination of Jane Austen biographers, some of whom see it as pivotal in her development as a novelist of courtship and self-knowledge and author of such beloved classics as Pride and Prejudice, Emma and Sense and Sensibility. Austen never married, dying at 41, possibly of Addison's disease, possibly of lymphoma.

The makers of Becoming Jane have used the known facts of the Lefroy case as a "jumping-off point for a fictional, fun romantic comedy in the Austen spirit." They've taken things we know about Austen's life and woven them together with characters and events from her novels. We'll never know exactly what happened between Jane and Tom; Becoming Jane spins out one scenario.

Here's what we do know from the letters. In a Jan. 9, 1796, missive to Cassandra — the first surviving letter — Jane reports on a dance she attended the night before. "I am almost afraid to tell you how my Irish friend and I behaved," she gushes. "Imagine to yourself everything most profligate and shocking in the way of dancing and sitting down together."

Tom, she reports, is "a very gentlemanlike, good-looking, pleasant young man, I assure you." Although the two apparently have seen each other only at three dances, their flirtation has made Tom the object of neighborhood teasing, she tells her sister.

Jane's letter-writing is interrupted by a visit from Tom and his cousin George. Afterward, picking up her pen, she jokingly tells Cassandra that Tom "has but one fault, which time will, I trust, entirely remove — it is that his morning coat is a great deal too light. He is a very great admirer of Tom Jones, and therefore wears the same coloured clothes, I imagine, which he did ... "

Whoa ... . Tom Jones?Henry Fielding's bawdy comic novel, a book people kept hidden under the mattress well into the 20th century? Have Jane and her beau been communing over TJ? This info-dollop catches biographers' eyes.

Claire Tomalin in Jane Austen: A Life writes, "Jane is making clear that she doesn't mind talking about a novel which deals candidly and comically with sexual attraction, fornication, bastard children and the oily hypocrisy of parsons, and roundly states that the sins of the flesh are of little account, and much to be preferred to the meanness of spirit of sober, prudent people." Jane is revealing to Cassandra "just how free and even bold their conversation has been."

Carol Shields in her short biography Jane Austen says the Tom Jones allusion "suggests a willingness to go beyond flirtation into an area of sensuous exploration."

This may seem heavy interpretive weight to hang on a mighty thin reed, but that's what biographers do. Blame Cassandra Austen for torching the rest of the evidence.

On Jan. 14, Jane, barely able to contain her excitement, writes that she "look[s] forward with great impatience" to the dance planned for the following night, "as I rather expect to receive an offer from my friend in the course of the evening." She adopts a bantering tone, adding "I shall refuse him, however, unless he promises to give away his white coat." But clearly Jane expects a marriage proposal. And as readers of Austen novels know, that's serious business, indeed. Jane tells Cassandra she's giving away her other admirers "as I mean to confine myself in future to Mr. Tom Lefroy, for whom I do not care a sixpence." We can take that last phrase as facetious.

By the next day, the joke had gone flat. The Lefroy family had stepped in. Jane writes, "At length the day is come on which I am to flirt my last with Tom Lefroy, and when you receive this it will be over. My tears flow as I write at the melancholy idea."

Biographer Jon Spence, for one, believes Tom and Jane saw each other again, once in London. But other biographies I've consulted make no reference to that, and Lefroy appears only one other time in the surviving letters. Three years after the romance, Tom's aunt visited the Austen parsonage but said nothing about her nephew. "I was too proud to make any enquiries," Jane writes to Cassandra, "but on my father's afterwards asking where he was, I learnt that he was gone back to London in his way to Ireland, where he is called to the Bar and means to practice."

As love affairs go, this one, in the retelling, doesn't sound like much. But it was the great romance in Jane Austen's life, and Tomalin and Shields say it changed her forever.

"From now on," Tomalin writes, "she carried in her own flesh and blood, and not just gleaned from books and plays, the knowledge of sexual vulnerability; of what it is to be entranced by the dangerous stranger, to hope, and to feel the blood warm; to wince; to withdraw; to long for what you are not going to have and had better not mention. Her writing becomes informed by this knowledge, running like a dark undercurrent beneath the comedy."

Shields thinks the episode recurs in various forms in Austen's novels, "embedded in the theme of thwarted love and loss of nerve."

"In the novels, happily, there is often a second or third chance, a triumphant overriding of class difference, but between Jane Austen and Tom Lefroy there is only silence."

And what of Mr. Lefroy?

He returned to Ireland, married a wealthy heiress, fathered seven children and grew pious. He prospered as a lawyer, won election to Parliament and in 1852 was appointed Lord Chief Justice of Ireland.

As an old man he was asked by his nephew if he'd really once been in love with Jane Austen. He replied yes, but that it had been "a boy's love."